Wireless Communication Techniques

ABSTRACT

Wireless communication techniques are described. In one or more implementations, techniques are described that involve active power control such that a device may bypass use of a power amplifier to communicate wirelessly. In one or more additional implementations, wireless communication techniques are described in which multiple bands may be leveraged to provide wireless communication. In one or more further implementations, wireless communication techniques are described in which a frame buffer on a receiving device is leveraged by a sending device. Yet further, in one or more implementations wireless communication techniques are described in which a sending device employs codec adaptation. Still yet further, in one or more implementations, wireless communication techniques are described which may be used to change characteristics of a channel used to communicate data. Yet further again, in one or more implementations, a receiving device is configured to adjust a display based on wireless communications received from a plurality of devices, such as to leverage a display by multiple wireless sources.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 61/430,639 (Attorney Docket No.331722.01) filed Jan. 7, 2011 and U.S. Provisional Patent ApplicationNo. 61/431,312 (Attorney Docket No. 332027.01) filed Jan. 10, 2011, theentire disclosure of each of these applications is hereby incorporatedby reference.

BACKGROUND

The prevalence of wireless communication is ever increasing. Originally,wireless communication techniques were employed by computing devicessuch as traditional desktop computers and laptops to communicate locallywith each other as well as remotely via the Internet. Use of thesetechniques was then expanded to a wide variety of other devices, such asgame consoles, input devices (e.g., keyboard and mouse), printers, andso on.

As this use expanded, however, traditional techniques that were employedto perform wireless communication were confronted with a wide range ofdifficulties. For example, the sheer prevalence of these techniques maycause interference between devices that employed the techniques therebylimiting the usefulness of the techniques to each of the devices thatemploy them. Further, the techniques may consume relatively largeamounts of power to overcome this interference, which may limitusefulness of the techniques to mobile devices that are powered by abattery and cause further interference.

SUMMARY

Wireless communication techniques are described. In one or moreimplementations, techniques are described that involve active powercontrol such that a device may bypass use of a power amplifier tocommunicate wirelessly. In one or more additional implementations,wireless communication techniques are described in which one or morestreams on a receiving device are leveraged by a sending device, such asthrough use of a buffer. In one or more further implementations, areceiving device is configured to adjust a display based on wirelesscommunications received from a plurality of devices.

Yet further, wireless communication techniques are described in whichmultiple bands may be leveraged to provide wireless communication. Yetfurther again, in one or more implementations wireless communicationtechniques are described in which a sending device may employ codecadaptation. Still yet further, in one or more implementations, wirelesscommunication techniques are described which may be used to changecharacteristics of a channel used to communicate data.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different instances in thedescription and the figures may indicate similar or identical items.

FIG. 1 is an illustration of an environment in an example implementationthat is operable to employ short and medium range wireless communicationtechniques.

FIG. 2 depicts a system in an example implementation in which acomputing device of FIG. 1 is configured to bypass and disable a poweramplifier for short range wireless communication.

FIG. 3 is a flow diagram depicting a procedure in an exampleimplementation of wireless communication techniques that relate tocontrol of a power amplifier to transmit data over different ranges.

FIG. 4 depicts a system in an example implementation in which existenceof a buffer and/or use of a data stream on a receiving device isleveraged by a sending device.

FIG. 5 is a flow diagram depicting a procedure in an exampleimplementation of wireless communication techniques that relate towireless buffering and stream usage techniques.

FIG. 6 depicts a system in an example implementation in which displaytechniques are employed in a wireless environment.

FIG. 7 is a flow diagram depicting a procedure in an exampleimplementation of wireless communication techniques that relate towireless display techniques for content received from a plurality ofdevices.

FIG. 8 illustrates an example system in which dual band functionality ofa wireless device is leveraged to provide wireless communication thatemploys both bands.

FIG. 9 is a flow diagram depicting a procedure in an exampleimplementation of wireless communication techniques that relate tocommunication functionality that leverage a plurality of bands.

FIG. 10 depicts a system in an example implementation in which wirelessencoding and decoding techniques are employed.

FIG. 11 is a flow diagram depicting a procedure in an exampleimplementation of wireless communication techniques that relate towireless encoding and decoding techniques.

DETAILED DESCRIPTION

Overview

The prevalence of devices that employ wireless communication is everincreasing. Consequently, traditional techniques that were employed toprovide wireless communication may be confronted with an ever increasingamount of interference between these devices, which may limit usefulnessof the communication techniques.

Wireless communication techniques are described. In one or moreimplementations, techniques are described that involve active powercontrol such that a device may bypass and disable the power amplifier tocommunicate wirelessly. The techniques may be employed by but are notlimited to short and medium range direct and indirect communication,such as Bluetooth, Wi-Fi (e.g., IEEE 802.11), Wi-Max, and so on. In thisway, power consumption by the device may be lessened in situations inwhich use of the power amplifier may be avoided, further discussion ofwhich may be found in relation to FIGS. 2 and 3.

In one or more implementations, wireless communication techniques aredescribed in which one or more frame buffers and/or streams on areceiving device are leveraged by a sending device. For example, thesending device may determine that a next frame matches a frame alreadysent to a receiving device and may then hibernate parts of the devicethat are used to transmit frames until a “new” frame is to be sent. Inthis way, power usage and network interference by the sending device maybe decreased, further discussion of which may be found in relation toFIGS. 4 and 5.

In one or more implementations, a receiving device is configured toadjust a display based on wireless communications received from aplurality of devices. For example, the receiving device may beconfigured as a television. The television may receive wirelesscommunications from a plurality of different devices, e.g., mobilephones. The television may then portion the display to display videofrom each of the devices. Further, the video sent by the devices may beconfigured according to how it is to be displayed by the display device,such as by adjusting a resolution and/or aspect ratio to match theportion in which the video is to be displayed. Further discussion ofthese techniques may be found in relation to FIGS. 6 and 7.

In one or more implementations, wireless communication techniques aredescribed in which multiple bands may be leveraged to provide wirelesscommunication. For example, a wireless device may have support for both2.4 GHz and 5.0 GHz bands. The device may be configured to employ bothbands to communicate with other devices, such as to employ the 2.4 GHzband to communicate control information and the 5.0 GHz band tocommunicate a data payload simultaneously, further discussion of whichmay be found in relation to FIGS. 8 and 9.

In one or more implementations, depending on the content type for thespecific frame, the codec type may be changed to a type that is bettersuited for handling a current information type. This may be performed byleveraging multiple processing techniques such as frequency profile,frequency gradients, temporal changes, edge change detection and othervideo and image progressing algorithms. Additionally, this may beperformed as part of a decision tree to select an appropriatecompression (e.g., codec) for use by the video frame, further discussionof which may be found in relation to FIGS. 10 and 11.

In one or more implementations, wireless communication techniques arealso described which may be used to change characteristics of a channelused to communicate data. For example, the sending device may detectnoise and renegotiate with a receiving device for a new channel, therebysaving power due to the increased cleanliness of the new channel andless retransmission of data. Other techniques are also contemplated,such as to dynamically adjust a compression ratio, an amount of change,change from one codec to another, beam forming, FEC (Forward ErrorCorrection) and so on, further discussion of which may be found inrelation to FIGS. 10 and 11.

In one or more implementations, wireless communication techniques aredescribed in which a sending device employs codec adaptation. Forexample, a sending device may determine whether a receiving devicesupports video in a current format. If so, the sending device maycommunicate the video without decoding it. If not, the sending devicemay transcode the video. In this way, the sending device may conserveresources that would otherwise be used to unnecessarily decode thevideo, further discussion of which may be found in relation to FIGS. 10and 11.

In the following discussion, example environments are described that maybe employed to perform the techniques described herein. Exampleprocedures are also described, which may be performed in the exampleenvironments and elsewhere. Accordingly, the example environments arenot limited to performance of the example procedures and the exampleprocedures are not limited to being performed in the exampleenvironments.

Example Wireless Environment

FIG. 1 is an illustration of an environment 100 in an exampleimplementation that is operable to employ the wireless communicationtechniques described herein. The illustrated environment 100 includes anaccess point 102, a computing device 104, and another computing device106 that are communicatively coupled via a wireless network 108.

The computing devices 104, 106 may be configured in a variety of ways.For example, the computing devices 104, 106 may be configured ascomputers that are capable of communicating over a wireless network 108,such as a desktop computer, a mobile station, an entertainmentappliance, a tablet, a set-top box communicatively coupled to a displaydevice, a wireless phone, a game console, a digital television, and soforth. Thus, the computing devices 104, 106 may range from full resourcedevices with substantial memory and processor resources (e.g., personalcomputers, game consoles) to a low-resource device with limited memoryand/or processing resources (e.g., traditional set-top boxes, hand-heldgame consoles, “dumb” digital televisions having limited functionality).

The computing devices 104, 106 may also include an entity (e.g.,software) that causes hardware of the computing devices 104, 106 toperform operations, e.g., processors, functional blocks, and so on. Forexample, the computing devices 104, 106 may include a computer-readablemedium that may be configured to maintain instructions that cause therespective computing device, and more particularly hardware of thecomputing devices 104, 106 to perform operations. Thus, the instructionsfunction to configure the hardware to perform the operations and in thisway result in transformation of the hardware to perform functions. Theinstructions may be provided by the computer-readable medium to thecomputing devices 104, 106 through a variety of differentconfigurations.

One such configuration of a computer-readable medium is signal bearingmedium and thus is configured to transmit the instructions (e.g., as acarrier wave) to the hardware of the computing device, such as via thenetwork 108. The computer-readable medium may also be configured as acomputer-readable storage medium and thus is not a signal bearingmedium. Examples of a computer-readable storage medium include arandom-access memory (RAM), read-only memory (ROM), an optical disc,flash memory, hard disk memory, and other memory devices that may usemagnetic, optical, and other techniques to store instructions and otherdata.

Although a single wireless network 108 is illustrated, the network mayassume a wide variety of configurations and may be configured to includemultiple networks, e.g., to support direct and/or indirectcommunication, follow different standards, and so on. The wirelessnetwork 108, for instance, may be configured for short rangecommunication, e.g., communication typically employed with a distance of10 meters. For example, the short range communications may be configuredto support direct and/or indirect communication within a room or betweenadjacent rooms of a structure such as a typical user's house.

The wireless network 108 may also be configured for medium rangecommunication such as in accordance with Wi-Fi (e.g., IEEE 802.11) fordistances of up to approximately 300 meters, WiMAX (e.g., IEEE 802.16)for distances of up to approximately 1 km, and so on. These standardsallow a variety of different computing devices (e.g., laptops, phones,games machines, and consumer electronics devices) to connect to theaccess point 102 and/or directly with each other to allow mobilecommunication of a variety of content, such as web content, mediacontent, email, messaging, and a variety of other data types. Forexample, a majority of mid to high end mobile communication devices mayleverage Wi-Fi to enable rich browsing, increased functionality forapplications, and data oriented communications. Thus, in each of theseexamples of short and medium range communication the wireless network108 is not a wireless telephone (e.g., cellular) network that istypically used for telephone communication, although suchimplementations are also contemplated.

The access point 102 and the computing devices 104, 106 are eachillustrated as including a respective communication module 110, 112,114. The communication modules 110, 112, 114 are representative offunctionality of the respective device to communicate over the wirelessnetwork 108. For example, the communication modules 110, 112, 114 mayrepresent functionality that may be used to encode data for transmissionas well as decode data received by the device in accordance with one ormore of the standards described above. The functionality may alsoinvolve techniques that may be used to manage communication, such as tonegotiate channels, resolve collisions, and so on.

As previously described, the variety of devices that employ wirelesscommunication techniques is ever increasing, such as laptops, digitaltelevision, smart phone platforms, optical disc players, and so on. Someof these devices may also employ a set of standards (e.g., from theDigital Living Network Alliance) to allow device discovery andconnection, media file browsing, and exchange of digital media such asphotos, music, and videos.

Accordingly, a variety of different techniques maybe used to communicatevia the wireless network 108. For example, communication may beperformed using the access point 102 such that the computing device 104transmits data through the access point 102 for receipt by the computingdevice 106. Direct communication between the computing devices 104, 106may also be supported that does not involve use of the access point 102or other device as an intermediary.

For instance, direct communication (e.g., Wi-Fi direct) may be leveragedto avoid costly dual path connections (e.g., up to access point 102 anddown from access point 102) of devices where principally point-to-pointconnections may be employed, e.g., when the computing devices 104, 106are within range of each other. This allows data types (e.g., video) tobe sent directly from a sending device (e.g., the computing device 104illustrated as a smart phone) directly to a receiving device, e.g., tothe computing device 106 illustrated as a digital television. Thus, thewireless network 108 may also represent communication that does notinvolve the access point 102. In an implementation, the computing device104 may also communicate with the access point 102 for web basedcontent, but the data from phone to digital television is nottransferred to the access point 102.

Additional standards may be employed in the environment 100 which relateto Wi-Fi display. For example, uncompressed standards (e.g., Wi-Gig) orcompressed standards (e.g., 802.11n) may be followed to transmit displayinformation such as video that may be displayed by a display device,such as the illustrated digital television. Wi-Fi display opens up anumber of opportunities beyond traditional media types to web pages,games, messaging, and so on. It may also be used to allow the sourcedevice (e.g., the computing device 104) to control the target display(e.g., computing device 106) thereby allowing a predictable andconsistent user experience. For instance, the source device (potentiallyalso multiple devices) may be used to drive each of the pixels on thetarget device, a portion of the pixels allotted to the source device,and so on as further described in the following discussion.

In the following sections, a number of power consumption and overallwireless network quality improvement techniques are discussed. Examplesof such techniques include “backing off” transmit power to a minimumlevel that is usable to successfully drive a wireless display device,avoiding use of a common frequency for wireless display and access pointtransactions, dynamically changing codec type and/or parameters, as wellas techniques usable to avoid transmission of redundant data between thedevices. Further discussion of these and other techniques may be foundin relation to the following sections.

Generally, any of the functions described herein can be implementedusing software, firmware, hardware (e.g., fixed logic circuitry), manualprocessing, or a combination of these implementations. The terms“module” and “functionality” as used herein generally representhardware, software, firmware, or a combination thereof. In the case of asoftware implementation, the module, functionality, or logic representsinstructions and hardware that performs operations specified by thehardware, e.g., one or more processors, functional blocks, and/orapplication specific integrated circuits.

Power Amplifier Techniques

FIG. 2 depicts a system 200 in an example implementation in which acomputing device 104 of FIG. 1 is configured to bypass and disable apower amplifier for wireless communication. The communication module 112of the computing device 104 is illustrated as including a communicationmanager module 202, a power amplifier 204, an antenna 206, a powersupply 208, and a switch 210.

In the illustrated example, Wi-Fi communications between the computingdevice 104 and the access point 102 may occur over a significant rangeas the access point 102 may be frequently located in a different room,different floor in a house, and so on. Consequently, in order to drivehigh bandwidth communications in such a situation, the output power fromthe accessing device may be relatively high. However, other situationsmay also be encountered, such as when the communicating devices (e.g.,the computing device 104 and another computing device 106) are located,in comparison, at a relatively close range to each other as illustrated.For example, in wireless display scenarios that involve both directcommunication between the devices and a relatively short distance (e.g.,under five meters), significantly lower power may be used while stilloperating at high bandwidths, e.g., at high Quadrature AmplitudeModulation (QAM) configurations, as would otherwise be the case whenoperating across a relatively longer distance. Therefore reducing the RFfootprint of a particular wireless communication system which willpermit greater frequency and/or channel reuse densities.

Accordingly, in this example the communication module 112 may adapt tochanges in range by measuring wireless link quality and adjusting poweroutput control on a regular basis, such as a packet-by-packet basis, atpredefined intervals, and so on. For example, the communication module112 may use pilot data sent during Wi-Fi handshake per packet datatransfer, RSSI signal strength information, use packet error conditionsto adjust rates, and so on. In one or more implementations, output powermay decrease values up to ten db and beyond using one or more of thesedata items and assuming a relatively close range (e.g., small distance)to the destination device, e.g., less than five meters.

In addition to power control, power consumption may be further reducedby bypassing the power amplifier 204, which although represented asinternal to the device may also be configured as an external amplifierand thus the switch 210 may be internally or externally deployed. Forexample, in some situations the power amplifier 204 employed by thecomputing device 104 may consume high static power even with low outputpower demands, such as when class AB amplifiers are used. Accordingly,the communication manager module 202 may employ a switch 210 to allowthe power amplifier 204 to be used for scenarios involving a relativelysignificant range, e.g., access point 102 scenarios that may involve asignificant distance. The communication manager module 202 may directlydrive the antenna 206 for Wi-Fi Direct circumstances (e.g., with thecomputing device 106 located at a relatively close distance) and bypassthe power amplifier 204 using the switch 210 to save power, which may beparticularly useful in mobile applications but may also be useful inother applications. For example, for power amplifiers that consume abase-load current these techniques may avoid significant powerconsumption even at low power levels, such as by employing the switch210 that may disable the power amplifier from the power supply 208,e.g., by “turning off” a supply rail to the power amplifier 204. Thus,the RF transmit power may be reduced to a minimal power level that issufficient to support a desired link quality, which therefore reducesthe RF footprint of the communication system.

Further, the use of relatively lower power may also result in areduction in noise in a wireless network 108, thereby further savingpower both for the device as well as other devices. For instance,disruption to other devices within the range of other devices thatengage in wireless communication may be reduced by having each devicereduce the amount of output power used, e.g., in office and other highdensity environments. Thus, if in an office environment, a number ofdevices within the 2.4 GHz/5 GHz unlicensed band range may share asingle frequency if the reduced RF power footprint is small enough tocreate a low-noise floor for the other devices. For example, wirelessdisplay functions may create significant band noise due to bandwidthutilization and thus decreasing the amount of power will reduce theradio frequency (RF) footprint and further minimize the disruption todevices on the same frequency. The smaller the RF footprint and the moreefficient the non-overlapping channel reuse is implemented the greaterthe density of wireless devices on the same frequencies can be realized.

FIG. 3 depicts a procedure 300 in an example implementation of wirelesscommunication techniques that relate to control of a power amplifier totransmit data. The following discussion describes techniques that may beimplemented utilizing the previously described systems and devices.Aspects of each of the procedures may be implemented in hardware,firmware, or software, or a combination thereof. The procedure is shownas a set of blocks that specify operations performed by one or moredevices and are not necessarily limited to the orders shown forperforming the operations by the respective blocks. In portions of thefollowing discussion, reference will be made to the environment 100 ofFIG. 1 and the system 200 of FIG. 2.

A sending device detects whether communications between a receivingdevice and the sending device comply with a predefined link quality(block 302). The detecting, for instance, may be based at least in parton an error rate or a scan of one or more wireless channels during oneor more non-transmit cycles. Further, the detecting may be performed ona per packet basis, at predefined intervals (e.g., based on number ofpackets transmitted, passage of predefined amounts of time), and so on.

Responsive to a determination that the communication comply with thepredefined link quality, a power amplifier of the sending device isbypassed to transmit a wireless communication to be received by thesending device (block 304). The determination, for instance, may bebased on the detection above. If it is determined that the receivingdevice is within range based on the predefined link quality, thecommunication manager module 202 may bypass the power amplifier 204using a switch 210 or other techniques and disable the power amplifiersuch that a supply rail to the power amplifier 204 from the power supply208 (e.g., a battery, “plug in” source, and so on) is disabled. Thecommunication manager module 202 may then communicate directly with theantenna 206 to transmit the wireless communication (e.g., one or morepackets) without the aid of the power amplifier 204. In this way, thesending device may reduce the amount of power used to perform thewireless communication, reduce an amount of interference caused by thewireless communication with other wireless devices that would otherwisebe within range of the interference, and so on.

However, responsive to a determination that communication do not complywith the predefined link quality, a power amplifier of the sendingdevice is used to transmit a wireless communication to be received bythe sending device (block 306). Thus in this instance, the sendingdevice may use the additional operational range afforded through use ofthe power amplifier 204, such as to comply with operational ranges ofIEEE standards.

Accordingly, a wireless communication may be received by a receivingdevice from the sending device that was communicated without using thepower amplifier of the sending device when the communication comply withthe predefined link quality (block 308). Thus, power used by the sendingdevice may be conserved and reduce interference caused by thecommunication. Additionally, a wireless communication may be received bya receiving device from the sending device that was communicated usingthe power amplifier of the sending device when the communications do notcomply with the predefined link quality (block 310). In this way, theoperational range of the computing device may be extended in instancesin which the devices are not within the predefined range.

Wireless Buffering and Streaming Techniques

FIG. 4 depicts a system 400 in an example implementation in whichexistence of a buffer on a receiving device is leveraged by a sendingdevice. In this illustrated example, a computing device 104 sends data(e.g., streams the data) via a wireless connection to the othercomputing device 106. The communication modules 112, 114 of therespective computing devices 104, 106 are shown in greater detail asincluding a respective communication manager modules 402, 404 andantennas 406, 408. The communication manager module 404 is furtherillustrated as including a frame buffer 410, which may be used to cacheframes to be rendered by the computing device 106.

Depending on the configuration there may be two or more frame buffersand/or streams, which may be used to support a number of wirelesssources as shown in FIG. 6. For example, at the wireless display theremay be a buffer and/or streams associated with each of the wireless A/Vsources being received by the display. Thus, the frame buffer 410 may berepresentative of a plurality of different frame buffers that may beutilized for a plurality of different streams. This data may then beprocessed (e.g., scaled) and merged into a master frame buffer and/orstreams that the display uses to generate a final image on the display.There are a variety of other techniques that may be used to handlemanagement of the multiple wireless video sources onto a single screenas further described in relation to FIG. 6.

A variety of traditional wireless display solutions involve powerconsumption above desirable targets for mobile applications, i.e., forcomputing devices that rely on a battery for power. Fortunately, manyscenarios include significant time periods when updates to the wirelessdisplay are unnecessary, e.g., for web browsing, instant messaging (IM),music, presentations that do not involve active animations, and so on.Traditional solutions, however, continue to transmit frames 412 withidentical content, thereby wasting power of both the sending andreceiving device as well as resulting in introducing additional andneedless noise to the environment that could be avoided.

In this example, additional control signaling by the communicationmanager module 402 of the sending computing device 104 and a framebuffer 410 of the receiving computing device 106 are leveraged such thatframes which have new content are transmitted from the source device butredundant frames are not, e.g., frames that have matching content.

In this case, the additional control signals contain control data tocause the wireless display to repeat a particular frame until a newframe is provided. The source transmission portion of module 112 maythen enter a sleep mode until a new frame is to be sent to the wirelessdisplay. Responsive to this, the internal frame buffer 410 may be usedto drive the target display until a new frame is sent. Beyond this,frame rates may be reduced from traditional (60 Hz/50 Hz) rates withlower frame rates being sent to the target display with associatedcontrol signals.

For example, a presentation may involve a relatively static display,e.g., a slide that does not change until an input is received.Accordingly, the system may send the frame but then determine that theinformation has not changed and therefore send a “repeat” command to thewireless display. The wireless display may then display this frame(e.g., over and over) until the source device sends a new frame. Duringthis period there may be little to no wireless video information sentand therefore the power consumed by the source device and noise thatotherwise may occur in the environment from transmitting the videoinformation is reduced.

Additionally, control signals may also be used to send the portions 414of the frame 412 that is being updated. This may work for a variety ofdifferent content, such as web pages with active portions (e.g., an ad)where the majority of the frame 412 is not active. Further, extenderconcepts may also be leveraged where video and audio streams are sentindependent to UI streams. Thus, when the overlaying UI frame is quiet,the video updates for the subsection of the display where video ispresented are sent. In additional embodiments, control data may also beused for animations and object manipulation.

FIG. 5 depicts a procedure 500 in an example implementation of wirelesscommunication techniques that relate to wireless buffering and streams.The following discussion describes techniques that may be implementedutilizing the previously described systems and devices. Aspects of eachof the procedures may be implemented in hardware, firmware, or software,or a combination thereof. The procedure is shown as a set of blocks thatspecify operations performed by one or more devices and are notnecessarily limited to the orders shown for performing the operations bythe respective blocks. In portions of the following discussion,reference will be made to the environment 100 of FIG. 1 and the system400 of FIG. 4.

A determination is made by a sending device that a second frame that isto be transmitted by the sending device to a receiving device includesat least a portion that is a repeat of a corresponding portion of afirst frame that was transmitted by the sending device to the receivingdevice (block 502). A communication manager module 402, for instance,may determine that a frame is repeated that is to be wirelesslytransmitted from the computing device 104 to another computing device106. The frame, for instance, may be part of a presentation or othercontent that includes a relatively static display of content.

Responsive to the determination, at least a portion of the first frame,which matches the portion of the second frame, is caused to be repeatedfor display by the receiving device without transmitted the portion ofthe second frame by the sending device (block 504). Continuing with theprevious example, the communication manager module 402 may form acontrol signal to cause the communication manager module 404 of thecomputing device 106 to repeat at least a portion of a frame stored in aframe buffer 410. In an implementation, the portion may encompass asubstantial display area of the frame. In another example, the sendingdevice does not send a control signal or a frame to the receivingdevice. The receiving device may then detect this lack of data (e.g.,frame and/or control signal) and therefore repeat a frame that hasalready been received by the receiving device. In this way, thereceiving device may act without receipt of data from the sending deviceto repeat a frame.

Also responsive to the determination, a sleep mode may be entered by oneor more hardware devices or subsystem of the sending device until anupdate to the first frame is to be transmitted to the receiving devicethat includes content that is not included in the first frame (block506). The communication manager module 402, for instance, may causehardware one or more components of the computing device 104 that areinvolved in wireless transmission to enter a sleep mode to reduce powerconsumption by the computing device 104. This may include reducing powersupplied to the hardware components but still keeping a baseline levelof power available such that the components may be quickly awakened.This may also include turning off a supply rail to the one or morecomponents to reduce power consumption completely or near completely. Avariety of other examples are also contemplated.

Further responsive to the determination, a transmission frame rate ofthe sending device to the receiving device may be reduced (block 508).The communication manager module 402, for instance, may determine that astatic display is to continue. Accordingly, the communication managermodule 402 may reduce the frame rate thereby conserving power andreducing interference in the wireless environment with other devicesthat engage in wireless communication.

One or more extender concepts may also be employed by the sending deviceto separate streams to be transmitted to the receiving device (block510). The extender concepts, for instance, may be configured to causevideo, audio and/or user interface streams to be transmitted separately.In this way, updates to each of these streams may be communicatedwithout involving the other streams.

Accordingly, the receiving device may receive one or more controlsignals and then repeat at least a portion of a frame stored in a framebuffer (block 512) as well as employ other of the previous describedtechniques for wireless communication described in the above blocks.Although examples of buffering and streaming techniques were described,a variety of other techniques may also be employed without departingfrom the spirit and scope thereof, examples of which may be found in thefollowing section.

Wireless Display Techniques

FIG. 6 depicts a system in an example implementation in which wirelessdisplay techniques are shown. In this example, two mobile computingdevices 602, 604 are in wireless communication with another computingdevice, illustrated as a display device 606. As stated in relation toFIG. 1, however, the computing devices may assume a wide variety ofother configurations.

The display device 606 as illustrated receives wireless data from themobile computing devices 602, 604. In response, the display device 606portions an available display area, which in this instance is to dividethe display area down the middle although other examples are alsocontemplated, such as to employ picture-in-picture techniques havingportions of various sizes that may be adjustable by a user of thedisplay device 606.

For example, for a three-dimensional display an entire display area ofthe display device may be used but configured to display particularcontent to particular users by leveraging glasses (e.g., LCD shutterglasses) typically worn by such users. Through synchronization betweenthe wireless display and the glasses, each user may view differentcontent and this display may appear simultaneous to the users.

Further, the sending devices may be configured to take advantage of thisportioning. For example, the mobile communication devices 602, 604 maybe configured to reformat the data being sent to the display device 706to have an aspect ratio, resolution, and so on that is configured toapproximate and even match the portions. In this way, the devices maysend a lesser amount of data than would otherwise be sent if the fulldisplay area was consumed by the data, e.g., video. A wide variety ofother implementations are also contemplated without departing from thespirit and scope thereof.

FIG. 7 depicts a procedure 700 in an example implementation of wirelesscommunication techniques that relate to display of content from aplurality of devices. The following discussion describes techniques thatmay be implemented utilizing the previously described systems anddevices. Aspects of each of the procedures may be implemented inhardware, firmware, or software, or a combination thereof. The procedureis shown as a set of blocks that specify operations performed by one ormore devices and are not necessarily limited to the orders shown forperforming the operations by the respective blocks. In portions of thefollowing discussion, reference will be made to the environment 100 ofFIG. 1 and the system 600 of FIG. 6.

Two or more streams are received wirelessly at a display device fromrespective two or more computing devices (block 702). As shown in FIG.6, for instance, the wireless display device 606 may receive streams ofcontent from first and second mobile computing devices 602, 604.

The display device may then automatically portion a display area of thedisplay device such that content from the two or more streams isdisplayable concurrently by the display device (block 704). Continuingwith the previous example, the display device 606 portions a displayarea into halves as illustrated such that content is displayableconcurrently from the plurality of mobile computing devices 602, 604.Further, picture-in-picture techniques may be employed such that a usermay change a size of the portions, reposition the portions, and so on. Avariety of other portioning techniques are also contemplated.

For example, the display area may be portioned so that a first stream isviewable using a first pair of three dimensional viewing glasses but nota second pair of three dimensional viewing glasses and content from asecond stream is viewable using the second pair of three dimensionalviewing glasses but not the first pair of three dimensional viewingglasses (block 706). In this example, the display device 606 may beconfigured for three-dimensional display through communication with thethree dimensional viewing glasses, e.g., LCD shutter glasses. In thisexample, larger portions may be displayed (e.g., overlapping even to thepoint of consuming an approximate entirety of the display area) andappear concurrent to two or more users, even though the users may viewdifferent content from different streams.

The data may also be reformatted by respective ones of the two or morecomputing devices according to respective portions via which the data isto be displayed by the display device (block 708). The display device606, for instance, may communicate with the mobile computing devices602, 604 to provide details regarding an available resolution, aspectratio, and so on of a portion that is to be used to display content fromthe device. The mobile computing devices 602, 604 may then format thecontent accordingly such that this reformatting may be “offloaded” fromthe display device 606. Other implementations are also contemplated,such as reformatting that is performed by the display device, use ofpredefined portions such that the reformatting may be performedautomatically and without user intervention by the mobile computingdevices, and so forth.

Dual Band Communication

FIG. 8 illustrates an example system 800 in which functionality of awireless device that involves a plurality of bands is leveraged toprovide wireless communication that employs two or more of the bands. Inthis illustrated system 800, the communication module 112 is shown ingreater detail as employing a communication manager module 802, a 2.4GHz band module 804, a 5.0 GHz band module 806, and respective antennas808, 810. Other implementations are also contemplated, such as use of adual-band antenna.

Techniques are described in the following that may be used to leverageindependent hardware that is available on many conventional devices tosupport a plurality of bands (e.g., both 5 GHz and 2.4 GHz bands)simultaneously, and without significant reconfiguration of the hardware.Traditionally, this radio frequency (not baseband) hardware of theseparate bands is not shared between the bands, although in some cases,a common phase-locked loop (PLL) is used but may be replicated by avendor. Accordingly, in one or more implementations wirelesscommunication techniques may be employed to leverage two or more bands,such as to communicate control information 812 over the 2.4 GHz band anda data payload 814 over the 5.0 GHz band.

In another example, a wireless channel within a band (e.g., 2.4 or 5.0GHz) may be used for audio/visual and associated control informationwhile another wireless channel within the band may be used for generalwireless networking traffic.

Adjacent channels, e.g., non overlapping channels, may also be usedwhere one is used primarily for access point internet data and thesecond is used for wireless display. For example, this may be performedin both 5 GHz and 2.4 GHz bands simultaneously to further increasebandwidth.

Techniques are also contemplated that use beacon signals to avoid lossof data sent to the device during Wi-Fi display operations. For example,the beacon may be checked for return data and used to interleave thetransmission for wireless display.

Further, as wireless display is transmission oriented for the most part,special packet ACK techniques may be leveraged on the receiving side(e.g., the wireless display) to reduce “listening” on the wirelessdisplay channel.

In an implementation, many of the baseband portions of the system may bedesigned to handle larger bandwidth (e.g., more than 20 MHz) with dual(e.g., 40 MHz) to multi-channel (802.11ac—80 MHz and beyond) solutions.Accordingly, this hardware may be multiplexed from its present dual+channel single orthogonal frequency division multiplexing (OFDM) streamto also handle dual independent OFDM streams, even if these occur atvery different frequencies since associated baseband data can be thesame. In other words, the Fast Fourier Transform (FFT) engines, Viterbi,and bit processing engines of the communication module 112 may processframes over two independent streams (e.g., access point 102 internetbased traffic and Wireless Display). Typically, antennas for 2.4 GHz and5 GHz are also different enough that separate antennas are used even ifpackaged in one component as illustrated.

In addition implementations systems may employ aspects of thisfunctionality that do or do not support concurrent 2.4 and 5 GHzoperation. For example, time-division multiplexing may be performedbetween bands. In another example, two channels in either 2.4 or 5 GHzband may be used. In an example implementation of the second example,two independent 20 MHz streams may be used. Again, one may run at highpower to communicate with an access point 102, but the second may uselow power to simply reach a relatively close computing device (e.g., adevice within a predefined range such that a power amplifier is notused) as described in relation to FIGS. 2 and 3.

FIG. 9 depicts a procedure 900 in an example implementation of wirelesscommunication techniques that relate to wireless communication thatleverages a plurality of bands. The following discussion describestechniques that may be implemented utilizing the previously describedsystems and devices. Aspects of each of the procedures may beimplemented in hardware, firmware, or software, or a combinationthereof. The procedure is shown as a set of blocks that specifyoperations performed by one or more devices and are not necessarilylimited to the orders shown for performing the operations by therespective blocks. In portions of the following discussion, referencewill be made to the environment 100 of FIG. 1 and the system 800 of FIG.8.

Data is obtained for communication from a sending device to a receivingdevice (block 902). The data, for instance, may be obtained throughexecution of one or more applications, received from another device,located in local or remote storage, and so on. Thus, the data mayoriginate from a variety of different sources.

First and second modules of the sending device are employed tocommunicate the data over the first and second bands simultaneously tothe receiving device (block 904), such as over 2.4 and 5.0 GHz bands.For example, each of the bands may utilize one or more channels tocommunicate with a same device, different devices, and so on.

The communication manager module 802 may also use a variety of othertechniques to perform this communication. For example, the communicationmanager module 802 may use the first module and corresponding first bandto communicate control information and the second module andcorresponding second band to communicate data (block 906). In anotherexample, the communication manager module 802 may use beacon signals tointerleave a transmission for wireless display by a wireless displaydevice (block 908) as previously described. Further, the communicationmanager module may handle a plurality of independent orthogonalfrequency division multiplexing (OFDM) streams using the first andsecond modules (block 910). For instance, the Fast Fourier Transform(FFT) engines, Viterbi, and bit processing engines of the communicationmodule 112 may process frames over two independent streams (e.g., accesspoint 102 internet based traffic and Wireless Display).

The communication manager module 802 may also employ time-divisionmultiplexing between the first and second bands (block 914). Thistime-division multiplexing may be performed by channels within a band,by the different bands, and so on. Further, the communication managermodule 802 may also employ techniques that were described in relation toother sections. For instance, the communication manager module may usethe first or second modules to vary an amount of power used by the firstor second modules based on whether a receiving device is within apredefined range (block 914). A variety of other examples are alsocontemplated without departing from the spirit and scope thereof.

Wireless Decoding Techniques

FIG. 10 depicts a system 1000 in an example implementation in whichwireless decoding techniques are employed. The computing device 104 andanother computing device 106 are illustrated as engaged in wirelesscommunication. The communication module 112 of the computing device 104is illustrated in greater detail as employing a communication managermodule 1002, a decoding module 1004, and an antenna 1006.

In this example, the communication module 112 is configured to determinewhether the receiving device (e.g., the computing device 106) is capableof decoding a source content format. If so, encoded data may becommunicated by the communication module 112 without being decoded bythe decoding module 1004. This also allows the target display to furtherimprove image quality if appropriate.

In scenarios where the type of displayed items may be identified, thecommunication manager module 1002 may employ different codecs and/orcodec rates to reduce the amount of traffic on the wirelesscommunication link. Because the wireless communication may be performedvia a packetized network (e.g., 802.11 standards), a reduction intraffic may also have a power and noise floor advantage. For gaming, forinstance, use of a H.264 encoder may be appropriate. For UI andsolutions that support object-like manipulation, wireless traffic maydrop dramatically by sending objects and animation control versussending data for each frame. For scenarios like Internet browsing,motion JPEG may be an alternative to preserve quality and data traffic.This may be performed by leveraging multiple processing techniques suchas frequency profile, frequency gradients, temporal changes, edge changedetection and other video and image progressing algorithms as part of adecision tree to select an appropriate codec (e.g., compressionalgorithm) for use in encoding the video frame.

Further, to minimize transmit RF power, different audio/visual (A/V)compression solutions for given types of media content may be used bythe communication manager module 1002. For example, compression type andratios may be adjusted on a per frame or sub frame basis to minimize theradio frequency (RF) power used to maintain a reliable RF link.

In an implementation, the devices (e.g., computing devices 104, 106)perform a scan to locate a possible 20 MHz in the target frequency bandthat is as “free” as possible in comparison with other bands beforestarting the link. This further allows spatial diversity of multiplewireless display users. This scan may also be done if high errorconditions occur in a band that is being used by the devices, when aclean channel is detected, in response to a request to change to the newcontention free channel is sent to the wireless display, and so on. Inaddition, beam forming may be used to reduce power requirements andminimize the RF Channel footprint for a given segment or spatial area.

In one or more implementations, a receiving device such as a wirelessdisplay may provide requests to a source device to change to a differentchannel. In response, the source may tell the receiving devices (e.g.,sinks) to which channel the device is to move. In this way, the sourcemay drive multiple receiving devices in a contention free manner,although other implementations are also contemplated in which thereceiving device is used to manage communication. For example, inscenarios in which multiple sources are driving into a single sink thiscould be reversed or a master source could be defined amongst thesources that specifies which channel to use for wireless communication,e.g., A/V transactions. In another example, the receiving device may bemade aware as to which data is missing (e.g., media frames) and providea recommendation to the sending device to change to a new channel once agiven threshold is exceeded.

FIG. 11 depicts a procedure 1100 in an example implementation ofwireless communication techniques that relate to communication offrames. The following discussion describes techniques that may beimplemented utilizing the previously described systems and devices.Aspects of each of the procedures may be implemented in hardware,firmware, or software, or a combination thereof. The procedure is shownas a set of blocks that specify operations performed by one or moredevices and are not necessarily limited to the orders shown forperforming the operations by the respective blocks. In portions of thefollowing discussion, reference will be made to the environment 100 ofFIG. 1 and the system 1000 of FIG. 10.

One or more frames are obtained by a sending device to be wirelesslytransmitted to a receiving device (block 1102). The frames, forinstance, may be generated by an application that is executed locally bythe computing device 112, from local storage of the computing device112, obtained remotely via a network, and so on.

A type of content is determined for one or more frames to be transmittedwirelessly by a sending device to a receiving device (block 1104). Forinstance, the frames may be involved in streaming video, part of apresentation, include scenes from a video game, obtained via a browser,part of execution of an application (e.g., a user interface), from avideo camera, and so forth. Accordingly, each of these types may havespecific characteristics that may be leveraged to reduce powerconsumption, noise and interference, and so on that may be involved inwireless communication of the frames. The determination may be performedin a variety of ways, such as based on a frequency profile, frequencygradients, temporal changes, edge change detection, and so forth.

A codec is identified to be used to encode the one or more frames basedat least in part on the determined type (block 1106). Responsive to adetermination that the one or more frames are not encoded using theidentified codec, the one or more frames are encoded using theidentified codec (block 1108). Continuing with the previous example,some types of codecs may be particularly suited for encoding particulartypes of frames. For gaming, for instance, a H.264 codec may be used toencode the frames. For user interfaces that support object-likemanipulation, wireless traffic may be reduced by sending objects andanimation control versus sending data for each frame. For scenarios likeInternet browsing, motion JPEG may be an alternative to preserve qualityand data traffic. A variety of other examples are also contemplated.

The one or more frames may also be compressed based at least in part onthe determination of the type of content (block 1110). For example, acodec or compression algorithm may also be chosen based oncharacteristics of the wireless channels that are used to transmit thedata. Further, this choice may be performed at a variety of time frames,such as at a per frame or sub-frame basis.

The sending device may also change to a different channel chosen by thesending device in response to a request received at the source devicefrom the receiving device (block 1112). For example, a receiving device(e.g., a wireless display device) may determine that there is a largeamount of noise on a current channel and therefore send a communicationto the sending device (e.g., a mobile device) to change the channel usedto communicate with the sending device. The sending device may thenchoose a new channel and communicate this information back to thereceiving device. Thus, in this example the sending device manages thewireless communication although other examples are also contemplated.

A variety of other wireless communication techniques are alsocontemplated, such as to dynamically adjust a compression ratio, anamount of change, change from one codec to another, beam forming, FEC(Forward Error Correction) and so on.

Mobile Device Wirelessly Sharing a Screen with Other Devices

Mobile communication devices have become increasing powerful and capableof being highly connected and capable of acting as relatively largestorage devices capable of complex tasks from gaming to photo editing.However, even though display devices employed by mobile communicationdevices have grown from average sizes below three inches in diagonal toclose to four inches, pan and zoom may still be involved when readingtypical web pages, emails, and so on. These devices are also typicallylimited in an ability to input content or control applications withlimited on-screen or small keyboards on these devices. Accordingly,techniques are described that may be used to enhance the input andoutput of the mobile communication device in circumstances where asecond display and/or input device is available.

In one or more implementations, the mobile communication devices may“remote” its display and input mechanism (e.g., touch, buttons, and soforth) to a simple display device via wireless display for the screencontent and a control back channel. This may be used to support avariety of different modes of operation:

-   -   1) Simple remote usage where the user simply sees a larger        device similar to tablet device. However, in this case, there is        no separate processor, memory, WAN communications, and so on        thereby allowing a lower cost, increased mobility, and ability        to synchronize. The experience may also be enhanced by allowing        a higher resolution display to be supported on the remote device        via scaling or direct rendering to the larger size.    -   2) The remote screen can be used as a display device, and the        phone with a copy (clone) on the display is used such that        control is accomplished from the phone.    -   3) The remote screen can act as a secondary display, and the        phone can display different content, contextual content,        keyboards, and so on. Control may occur from both the remote        display and phone.        In the first cases, the phone may stay in one's pocket. In        cases 2) and 3) the remote may sit on a surface, located in a        dock, physically connected to the phone, and so forth.

A variety of different functionality may be supported by thesetechniques, such as an ability to remote phone interface via optimizedwireless display mechanisms (e.g., optimized link, remote UI, animation,and display compression) where applications can run completely on thephone, but interfaced to the user on the remote display. Additionally,compressed videos may be embedded to be natively decoded by remotedisplay, remotely execute UI animation, and adjust decoding based oncontent on remote side.

Further, touch (e.g., multiple finger gesture) and button clicks may beembedded into a reverse channel of the mobile communication device, andthese commands may be replayed as if they were natively executed on themobile communication device. A conversion may also be made on the remotedevice to convert touch points from remote coordinates to nativecoordinates on the mobile communication device. Further, thesetechniques may leverage integrated Wi-Fi/decoder solution which providescommunications, content decoding, embedded frame buffer solution, andcontroller that is cost efficient.

Traditionally, customers would either use their phone or laptop foreverything from web browsing to games to reading email. Recently,however, a third device commonly referred to as a “tablet” have becomepopular that have a screen size between phones and laptops, higherbattery life than both, touch interfaces and applications similar tosmart phones, and thickness similar to smart phones. These devices allowusers a third choice, but may have significant costs (e.g., both deviceand carrier costs), synchronization issues, and in some casessignificant user interface differences. The proposed solution allowscustomers the option to have an internet tablet at significantly lowercosts, which is synchronized with their smart phone, and provides acommon user interface.

The solution may leverage techniques to identify, connect, encode,transmit, and decode/display remotely. Standards such as 802.11, Wi-FiDirect, uPNP, H.264, Motion JPEG, and so on may be leveraged.

To build a remote tablet, a small portion of a typical internet tabletmay be used to construct a “thin” device. For example, the tablet may bemanufactured without an applications processor, large flash or DRAM, WANmodem, and so on. Further, the remote tablet may employ a relativelysmaller battery, have Wi-Fi, similar display, and leverage decoders anda relatively small controller yet still provide a majority of typicalinternet tablet functions. The remote display, when using the phone asthe source device, may be able to provide this experience however on alarger display. If one excludes the display, these costs can representbetween twenty and fifty percent of the typical electrical bill ofmaterials of an internet tablet.

Further, the return channel may be employed for set-up andacknowledgement of packets. As events from a touch controller or buttonsoccur, these come to the small controller to be translated and encoded.These may then be sent to the mobile communication device to avoidlatency between displayed objects and touch events. Once received, themobile communication device may decode these events as if received fromits touch controller. For dual screen scenarios, the touch events may bereceived as second touch controller.

Wi-Fi beacon signals or BT may also be used to allow wake up of themobile communication device from the remote device. Power may also beshut-down on both sides after user controllable time periods ofin-operation.

Further, the mobile communication device's graphics processing unit maybe used to render not only to the local display size, but also to alarger resolution allowing better viewing of applications, web content,and so forth.

Negotiation between mobile communication device and the remote tabletmay be used to identify which compression types are permitted. Forexample, applications may have their rendered content encoded in eitherH.264 or motion JPEG after a frame has been completed. In this example,the application is not made aware that the frame is being transmittedfor remote viewing. For cases where a media player is used (or anembedded media player like in a web page is called), the encoded mediastream may be captured before being decoded on the mobile communicationdevice. The stream is then encapsulated, and sent to the remote deviceto either be decoded either within a graphics frame decoded and mergedor simply decoded full screen. Other types may also be more efficientlyencoded/decoded based on data type, but this may involve greaterawareness by applications of the remote device and potentially morecosts in the remote device.

Audio streams may also be embedded in either direction to supportapplications like conference calls, media playback, and voice commands.

Mobile Device Broadcast to Multiple Wireless Displays

To display content on multiple displays using traditional techniquesinvolved the use of splitters, and cables that were routed to individualdisplays. This presents a problem of setup difficulties and thissolution is meant to address this problem. Traditional wirelesssolutions (e.g., over short to medium distances) do not supportbroadcasting to multiple displays. This solution allows a mobilecommunication device to broadcast its content wirelessly to multipledevices.

The mobile device (e.g., which may also be referred to as a sourcedevice) using the techniques described herein is capable of broadcastingits content (whether it is an audio/video, pictures, data, screendisplay, or others) to multiple wireless displays (shall now be known assink devices) at the same time. In this way, broadcasting of contentfrom a source device to multiple sink devices at the same time may besupported.

For example, a user may initiate the broadcast feature on the sourcedevice and select which sink devices to which the content is to bebroadcast. The user may then select multiple sink devices within rangeof the source device. Once the links between the source device and thesink devices are established, the user can then choose the content onthe source device to be broadcast. For instance, the user may select tobroadcast the source device's screen content to the sink devices. Inthis case, if the user is playing an audio/video content on the sourcedevice, while it's content is also broadcast to the sink devices. Uponreception of the content, the sink devices may then display the contentof the source device. The links between the source device and sinkdevices may be bidirectional to allow the handling of packet errors,link controls, data transport, service establishments, and so forth.

Mobile Device Wireless Screen Share with Other Devices

This technique allows a user to share screen content of a device(whether it be pictures, audio/video, data, etc.) with multiple deviceswhen the link between the devices are established. This allows otherdevices to display the shared content along side with the local contenton the device.

For example, the mobile device (shall now be known as source device) iscapable of wirelessly screen sharing its content (whether it is anaudio/video, pictures, data, screen display, or others) with otherdevices (shall now be known as sink devices) and vice versa. This allowsthe sink device to view its local content and the shared content. Theshared content screen size can be adjusted on the sink device. Thus, avariety of different functionality may be supported by these techniques:

-   -   Wirelessly share screen content from a source device to multiple        sink devices when the devices are within their wireless range.    -   Allow the sink device to view the local content and shared        content.    -   Shared content screen size is adjustable on the sink device.

The devices are not limited to laptops, desktops, wireless display,tablets, slates, and mobile devices. The source device may be defined asa device providing content to be shared. The sink device may be definedas a device receiving the shared content. During a screen sharingsession, multiple sink devices may be allowed but a single device isdesignated as a source.

In this context, the user initiates the screen sharing session on eachof the devices. One of the devices is specified as the source device,and the other devices are configured to be the sink devices. Uponestablishing the screen sharing session between the devices, the sinkdevice can display the shared content on its screen.

The shared content screen size on the sink devices can be configured bythe user to full screen (maximize size) or restored screen (adjustablesize). During the screen sharing session, any one of the sink devicescan become the source device by requesting role changes. Upon finalnegotiation of the role changes, the devices are reconfiguredaccordingly and the new content sharing begins.

Mobile Device Audio Synchronization with a Wireless Display

When a device provides a video stream to a wireless display, while theend user is listening to the audio at the device end, the audio andvideo may be out of sync. This may be due to latency in the compression,transmission and decompression which varies depending on RF environmentand video processing.

To enhance the audio & video (A/V) synchronization when the sourcedevice is providing content to a wireless display while the audiocontent is being played locally, a mechanism may be employed todynamically synchronize the A/V content. For example, an audio bufferand/or stream may be used that dynamically adjusts the play point and/orrate to account for the system latency to ensure the audio at the sourceis synchronized with the video at the remote end point.

There are a variety of different mechanisms that may be utilized. Forexample, if the source device supports a microphone the audio buffercontrol system may compare a test tone being received locally by thatoriginating from the display. The tone, for instance, may be implementedas a relatively short burst outside the human acoustic range and/orimperceptible short duration. The control system may then measure thelatency and adjust the audio buffer play state and/or rate appropriatelyto align the A/V.

In another example, the source device may transmit a RF timing packet tothe end point at the display. The end point may then respond and thesource devices may measure the RF delay. The round trip time coupledwith the known or estimated encode & decode latency may be summedtogether to provide the total system latency measure for packet latency.A variety of other examples are also contemplated.

Conclusion

Although the invention has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the invention defined in the appended claims is not necessarilylimited to the specific features or acts described. Rather, the specificfeatures and acts are disclosed as example forms of implementing theclaimed invention.

1. An apparatus comprising: a first module that is configured tocommunicate over a first band for wireless communication; a secondmodule that is configured to communicate over a second band for wirelesscommunication; and a communication manager module that is configured tomanage simultaneous wireless communication over the first and secondbands using the first and second modules.
 2. An apparatus as describedin claim 1, wherein the first module is configured to communicate over a2.4 GHz band and the second module is configured to communicate over a5.0 GHz band.
 3. An apparatus as described in claim 1, wherein thecommunication manager module is configured to utilize the first moduleand corresponding first band to communicate control information and thesecond module and corresponding second band to communicate data.
 4. Anapparatus as described in claim 1, wherein the communication managermodule is configured to utilize a wireless channel within the first bandfor audio/visual data and associated control information and anotherwireless channel for other wireless networking traffic.
 5. An apparatusas described in claim 1, wherein the communication manager module isconfigured to utilize a wireless channel within the first band forwireless display data and another wireless channel for access pointinternet data.
 6. An apparatus as described in claim 1, wherein thecommunication manager module is configured to utilize beacon signals tointerleave a transmission for wireless display by a wireless displaydevice.
 7. An apparatus as described in claim 1, wherein thecommunication manager module is configured to handle a plurality ofindependent orthogonal frequency division multiplexing (OFDM) streamsusing the first and second modules.
 8. An apparatus as described inclaim 1, wherein the communication manager module is configured toemploy time-division multiplexing between the first and second bands. 9.An apparatus as described in claim 1, wherein the communication managermodule is configured to perform wireless communication utilizing thefirst or second modules that involves varying an amount of power used bythe first or second modules based on whether communications between areceiving device and the apparatus comply with a predefined linkquality.
 10. An apparatus as described in claim 9, wherein thepredefined link quality is based at least in part on an error rate or ascan of the channels during one or more non-transmit cycles.
 11. Amethod comprising: determining a type of content for one or more framesto be transmitted wirelessly by a sending device to a receiving device;identifying a codec to be used to encode the one or more frames based atleast in part on the determined type; and responsive to a determinationthat the one or more frames are not encoded using the identified codec,encoding the one or more frames using the identified codec.
 12. A methodas described in claim 11, wherein the determining is based at least inpart on frequency profile, frequency gradients, temporal changes, oredge change detection.
 13. A method as described in claim 11, whereinthe determined types describe whether the content involves a video game,a user interface that supports object-like manipulation, or motion videothat relates to Internet browsing.
 14. A method as described in claim11, further comprising compressing the one or more frames based at leastin part on the determination of the type of content.
 15. A method asdescribed in claim 14, wherein the compressing includes selection of acompression type or a compression ratio based on the determination ofthe type of content.
 16. A method as described in claim 15, wherein thecompression type or ratio is adjusted on a per frame or sub-frame basis.17. A method as described in claim 11, further comprising changing to adifferent channel chosen by the sending device in response to a requestreceived at the source device from the receiving device.
 18. A method asdescribed in claim 11, wherein the identifying includes determining ifthe codec is supported by the receiving device.
 19. A method comprising:determining a type of content for one or more frames to be transmittedwirelessly by a sending device to a receiving device; and compressingthe one or more frames based at least in part on the determination ofthe type of content.
 20. A method as described in claim 19, wherein thecompressing includes selection of a compression type or a compressionratio based on the determination of the type of content.